A conveyor system is used as material handling equipment in many different industries. Examples of conveying devices are belt conveyers, chain conveyers, vibrating conveyers and link conveyers. Pneumatic conveying is the process of transporting bulk materials in a gas stream, for example air or nitrogen, through a pipeline.
When a pneumatic conveying system is delivering material, for example fuel or raw materials, to a process that frequently requires an adjustment in the pneumatic conveying feed rate, the response time possible from the pneumatic conveying system is limited by how quickly material can travel through the pipeline. When the conveying distances typically exceed for example 200m, with an average conveying velocity of 10 m/s, it takes an average 20 seconds for the conveying rate to start to increase at the process located at the end of the 200 m conveying pipeline. If the conveying rate then takes, for example, a further 30 seconds to increase from the lowest to the highest feed rate at the start of the pipeline, due to physical limitations over how the feed device can be operated, then it can typically take e.g. 50 seconds in practice for the maximum feed rate to be seen at the process.
Other factors such as how quickly the pressure in the conveying system over such a distance can be raised, the risk of pipeline blockages, or the impact of higher velocity's creating additional wear or material damage, can further limit the response time possible from a pneumatic conveying system directly feeding a process connected to the end of the conveying pipeline.
In order to solve these problems, often a large volume (typically 30 minutes up to several hours worth at maximum capacity) of material is stored directly adjacent to the feed point to the process. However, this is often compromised by the size and cost of the storage at the feed point, or is not possible due to an absence of space especially in complex processes, or in process plant that already exists and whose design and construction is not easily changed or adapted.
It is desirable to provide an improved pneumatic conveying system; one, which at least mitigates one or more of the above problems.
It is desirable to provide an improved pneumatic conveying system which can more rapidly increase or decrease feed rate compared with typical pneumatic conveying arrangements, without a relatively large amount of material storage directly at the process feed point.